AbstractAs we move towards the vision of a next generation Web, be it called Web 2.0 or Semantic Web, we observe that the number of formats used for representing data on the Web increases, so does apparently the languages we are supposed to use to access that data: XPath, XQuery, SPARQL, XSLT, Xcerpt, etc. In this deliverable we propose a formal foundation for most common Web formats and query languages by introducing a formal query language, called CIQLog operating on data graphs and translating Xcerpt, XPath, XQuery, and SPARQL into that language. Not only do we arrive at purely logical semantics for these languages and a better understanding of their differences, we also pave the way to space and time optimal implementations of these languages by means of the CIQCAG algebra introduced in the second part of this deliverable.